One knows already such push-buttons and such keyboards with depressable keys and magnetic return means, which have the advantage, relative to the known prior devices, of not using a return spring, and therefore of not presenting the disadvantages associated therewith (loss of rigidity, fatigue phenomenon, resonance phenomenon, sensitivity to corrosion, return force increasing in proportion to the path covered by the key or push-button when being depressed, sensitivity to vibrations and accelerations, etc.).
Said push-buttons and keyboards with keys and magnetic return means have nevertheless the disadvantage that the duration of the signal produced by depressing the push-button or key is far shorter than the total operation time of the push-button or key. In some applications, it is necessary that the signal has a duration representing at least 60% of the total operation time of the push-button or key.